<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      function person() {
        console.log("hello person");
      }
      // person.prototype.constructor = null;
      // person.prototype = null;

      // person.prototype.username = "jack";
      // person.prototype.age = 20;
      person.prototype = {
        username: "jack",
        age: 20,
        constructor: person,
      };
      person();
      person.prototype.constructor();
      console.log(person.prototype);
    </script>
  </body>
</html>
